P0500 - 2003 Mazda Protege

Backyard mechanic cooled down the engine with water in order to quickly swap an alternator.

Alternator swap was fine, but on the drive home the check engine light and the AT light both started flashing.

At the suggestion of the mechanic (a relative!) I pulled the coil packs and the spark plug wires and let them dry out overnight. This resolved the misfire issue and the car now idles properly.

However, the Speedo doesn’t work and the transmission doesn’t shift properly, feels like the rev limiter is kicking in at 2000 RPMs. It will drive fine once it gets up to cruising speed on the highway, but sometimes during in town driving it will take a long while to get up to speed.

I’ve pulled the code and it comes up P0500. I pulled and used a can of compressed air on all of the connectors I can find, I pulled and cleaned the VSS, and the error still pops up.

I tested the voltage coming to the VSS and it looks like there’s an open circuit there somewhere. The manual says I should be getting 12v and the meter is reading .5.

What should I be looking at now?